1. Field of the Invention
This invention relates to a digital noise shaping circuit. More particularly, this invention relates to a fourth order digital noise shaping circuit for use in a digital-to-analog conversion circuit.
2. Brief Description of the Related Technology
Typically, digital-to-analog converter circuits (DACs) operate by a resistor/capacitor divider method, or use a sigma-delta conversion method, to convert digital signals to analog signals. Sigma-delta DACs are preferred because of their inherent feasibility to be manufactured in integrated circuits. These DACs typically create 1-bit signals from multi-bit digital input signals. This quantization, if performed by merely truncating or rounding the multi-bit signal, would introduce a large amount of noise in the signal passband, thereby destroying the signal quality. Noise shaping pushes the quantization noise out of the signal passband. Also, the 1-bit signal can be converted to an analog signal with no linearity errors.